The invention relates to a reversible draw-in and draw-out mechanism for an extractible multipole electrical circuit breaker, equipped with main circuits with terminals and auxiliary circuits associated with a connection device having fixed connectors and interacting movable connectors, the circuit breaker being mounted on a movable mechanical support inside a fixed chassis in the form of a housing having a front opening, two opposite side walls, and a fixed rear support panel for connection of the main terminals of each pole, the mechanical support of the circuit breaker being guided by means of a pair of slide plates symmetrically fixed to the side walls of the chassis and extending parallel in the longitudinal draw-in direction, said mechanism comprising an operating device associated with a movement transmission system capable of occupying a first "draw-in" position in which the main and auxiliary circuits of the circuit breaker are connected, a second "test" position in which the main circuits are disconnected and the auxiliary circuits are connected, and a third "drawn-out" position in which the main and auxiliary circuits are disconnected.
According to a state of the art draw-out circuit breaker of the kind mentioned, one of the auxiliary circuit connectors is fixed to the circuit breaker on the same wall through which the main circuit terminals pass, and the interacting connector is securedly attached to the connection support panel. Connection and disconnection of the auxiliary circuit connectors take place in the direction of movement of the circuit breaker. The movement transmission system forms a permanent desmodromic link between the operating device and the movable mechanical support of the circuit breaker. In the course of actuation of the mechanism, the circuit breaker occupies three distinct positions, staggered along the longitudinal draw-in direction. Each position of the circuit breaker corresponds to one of the drawn-in, test or drawn-out positions of the main and auxiliary circuits. The presence of these three positions gives rise to an increased draw-in travel and opposite draw-out travel and results in the chassis having large dimensions.
Most draw-out circuit breakers comprise in addition a fixed chassis equiped with the connection support panel and a pair of retractable rails on which rolling parts securedly united to the circuit breaker can run. The latter is generally surrounded by an auxiliary metal frame whose opposite side walls support the rolling parts, the whole assembly being able to move inside the fixed chassis when the racking mechanism is actuated. The presence of this auxiliary metal frame complicates fitting of the circuit breaker guiding and locking means, and contributes to increasing the price and weight of the apparatus.
A first object of the present invention is to reduce the travel of the draw-out circuit breaker in order to reduce the dimensions of the chassis.
A second object of the present invention is to simplify the support and locking devices of a draw-out circuit breaker.